Try to wear wide, comfortable and stretchy underwear during late pregnancy. Bras are optional for everyone to wear because late pregnancy breasts generally have more fatty tissue in them than before pregnancy, and the milk ducts as well as the mammary glands are beginning to develop, but pregnant women should try to wear maternity bras. Strictly speaking, it is not recommended to wear a bra when sleeping during pregnancy because turning over at night is an inevitable physical action. According to statistics, the average person will turn over more than 20 times at night, and during the turning process the bra will be shifted, which will cause the sagging or expansion of the chest, while turning over without a bra has less impact on blood circulation. In addition, wearing a bra to sleep is more likely to cause breast cancer. Therefore, you should not wear a bra to bed during pregnancy. You can wear a maternity bra during the day.